Did Stripe require that some specific feature was added or fixed? Especially if they did, that $3750 is a small amount of money to pay get some functionality to work. Not to mention, that they get some nice publicity from this.
Regardless, kudos for Stripe for sponsoring open source projects.
I think all parties win in this, not just Stripe. Urrlib3 developer and users (new features and enhancments), and the whole FOSS community (if more and more companies start doing this). Also if the competition is fierce for the top talent, doing these kind of "support the community" acts, surely won't be seen as negative things for the company that does these things.
So kudos indeed for Stripe! Let's hope this comes "a thing"
Regardless, kudos for Stripe for sponsoring open source projects.